2. The table below describes data set concerning the effect of tobacco use on BMD (Bone Mineral Density). For each pair twins, compute the following for the lumbar spine: A=BMD for the heavier-smoking twin - BMD for the lighter- smoking twin = XI-X2 B=mean BMD for the twinship = (XI-X2)2 C= 100% x (A/B) Twin 1 Lighter Smoking Twin ht1 15-19 Height (cm) wt1 20-24 Weight (kg) teal 25-29 Tea (cups/week) cofi 30-34 Coffee (cups/week) alc! 35-39 Alcohol (drinks/week) cur1 40-44 Current Smoking (cigarettes/day) men! 45-49 Menopause Status (0 pre/l-post/2-unknown hysterectomy) pyr1 50-55 Pack-years smoking Isl 56-61 Lumbar spine (g/cm**2) fnl 62-67 Femoral neck (g/cm**2) fs1 68-73 Femoral shaft (g/cm**2) Twin 2 Heavier Smoking Twin ht2 74-78 Height (cm) wt2 79-83 Weight (kg) tea2 84-88 Tea (cups/week) cof2 89-93 Coffee (cups/week) alc2 94-98 Alcohol (drinks/week) cur2 99-103 Current Smoking (cigarettes/day) men2 104-108 Menopause Status (0=pre/l=post/2=unknown hysterectomy) pyr2 109-114 Pack-years smoking 1s2 115-120 Lumbar spine (g/cm**2) fn2 121-126 Femoral neck (g/cm**2) fs2 127-132 Femoral shaft (g/cm**2)